1. Field of the Invention
The invention relates to a technology of elevating the temperature of a power storage device, using ripple current.
2. Description of Related Art
It is known that, as the temperature of a secondary battery decreases, the internal resistance of the secondary battery increases, and the output of the secondary battery is reduced. If the secondary battery is warmed up, the internal resistance of the secondary battery can be reduced, and sufficient power can be generated by the secondary battery. Technologies concerning the temperature of the secondary battery are described in, for example, Japanese Patent Application Publication No. 2008-092624 (JP 2008-092624 A), Japanese Patent Application Publication No. 2011-015544 (JP 2011-015544 A), Japanese Patent Application Publication No. 2010-257722 (JP 2010-25722 A), and Japanese Patent Application Publication No. 07-142095 (JP 07-142095 A).
The secondary battery may be charged with electric power supplied from another power supply. When the secondary battery is charged in this manner, the secondary battery may have to be warmed up. In this case, it is preferable to perform charging of the secondary battery and warming of the secondary battery with high efficiency.